Comment 3 for bug 1209199

Hi Edward,
       At first, I really think this shoud goes to BP rather than a bug report.
       For the three user scenarios you listed , (a) and (c) now already supported , there is a bool flag in configuration(rbd_flatten_volume_from_snapshot) available there,if you want a full copy( scenario a) ,you could set it to True, otherwise set it to false(scenario c). So Basically what your add-on is to support scenarios b.
      Scenario b, as you said, is a tradeoff between creation time and performance, but ,althought it's very clear how this value impact the creation time, we still have no insight about how it affect performance. User will also confused about how to set this value, for example ,if I want best read performance and I don't care about the write performance, shoud I set it to 0 or infinity? increasing the value should slow down the creation time, but can I get better performance ? is there a reasonable /meaningful default value? The answers are all Unknown to me, and also to most of the users.
      So my opinions are:
1. let's move this to BP
2. I am -1 for this unless we(Ceph users) have very clear mind about what the trade off is.It's not a good idea to leave a magic tuneable there for user.